1. Field of the Invention
The present invention relates to a terminal structure, and, more particularly, relates to a specific terminal structure, wherein a metal plate is turned away from a metal terminal against the spring action of a torsion coil spring while an electrically conductive wire is inserted. If the action is applied to the electrically conductive wire to be pulled out from the structure, the metal plate is turned towards the metal terminal thereby to press the electrically conductive wire against the metal terminal with a stronger force and secure the electric conduction between the metal terminal and the wire. The torsion coil spring of a specific elasticity normally gives such pressure as to hold the electrically conductive wire and the metal terminal in an electrically stabilized conductive condition. Further the electrically conductive wire may be attached and detached with one-touch light operating action.
2. Description of the Related Art
To date, various terminal structures have been proposed wherein an electrically conductive wire may be easily connected to the structure with one-touch operating action. For example, the terminal structure 1 shown in FIG. 15 is composed of an electrically isolated case 2 of synthetic resin. The terminal structure has a metal terminal 3 secured to and within the case 2 by a pair of extensions 3a being protruded out of the case. A metal plate 4, that is, a substantially U-shaped plate spring, has a center portion 4a mounted on a pin 2a formed on the case 2, has one end 4b engaging an inner surface 2b, and has the opposite end 4c pressed against the metal terminal 3. Further, an operating pin 5 is slidably inserted into a guide hole 2c formed within the case 2.
If the operating pin 5 is pressed from the outside of the case 2, the inner end 5a of the operating pin 5 presses the end 4c of the metal plate 4 against the spring action thereof in the direction away from the terminal 3. Thus the electrically conductive wire (not shown) may be inserted into between the metal terminal 3 and the metal plate 4 through a wire guide hole 2d formed within the case 2. Upon freeing the operating pin 5, the metal plate 4 returns with its elasticity to press the electrically conductive wire against the metal plate 3, thereby to secure the electric conduction between the electrically conductive wire and the metal plate 3.
However, according to the conventional terminal structure 1 having the plate spring 4 used to apply pressure to the electrically conductive wire, the user is required to press such a small operating pin 5 against the strong spring action of the plate spring in order to insert the electrically conductive wire into the structure 1 or to pull out the same therefrom. Therefore the operation of the operating pin 5 will cause pain to the finger of the user and the operability is extremely bad. As the result, the user often fails to press the operating pin 5 deep enough allowing the electrically conductive wire to be forcibly pulled out of the case with the resultant damages given to the terminal structure 1.
Another conventional terminal structure 10, as shown in FIG. 16, is composed of an electrically isolated case 11 of synthetic resin. The terminal structure has a U-shaped metal terminal 12 secured to and within the case 11 by a pair of extensions protruded out of the case. A metal plate 13 has one end formed in a ring 13a and has an opposite flat end 13b. The metal plate 13 is, at the ring 13a, turnably mounted on a support pin 11a formed on the case 11 so that the metal plate 13 may be turnable with respect to the metal terminal 12. A compression coil spring 14 is provided between the case 11 and the metal plate 13 so that the compression coil spring 14 may press the flat end 13b of the metal plate 13 against the metal terminal 12. Further an operating pin 15 is slidably inserted into a guide hole 11b formed within the case 11.
According to the conventional terminal structure 10, especially having the compression coil spring 14 used in such a way that one end of the compression coil spring 14 is simply pressed against the metal plate 13, the end of the compression coil spring 14 is actually liable to slide with respect to the metal plate 13. It therefore often happens that the position where the compression coil spring 14 applies the pressure to the metal plate 13 will change each time the operating pin 15 is pressingly operated. As the result, it becomes difficult to hold the electrically conductive wire with a constantly stabilized pressure.